Search Results (219)

A simple and efficient dispersive micro solid-phase extraction (DMSPE) method using nano-TiO₂ as a sorbent was developed for the separation and preconcentration of (ultra) trace levels of lead in water samples prior to quantification by electrothermal atomic absorption spectrometry (ETAAS). Key experimental parameters affecting the DMSPE process, including pH, ionic strength, sorbent dosage, and preconcentration factor, were optimized. The optimized method demonstrated a preconcentration factor of 20, a relative standard deviation below 4.5%, and a detection limit of 0.11 µg/L. The procedure was validated using certified reference material (CRM TM-25.5) and applied to real water samples from a lake, a residential well, and industrial wastewater. Satisfactory recoveries (89–103%) confirmed the reliability of the method for the determination of low lead concentrations in complex matrices. Full article

This dataset presents environmental observations collected in August 2021 from 18 port and harbor sites located around Jeju Island, Korea. It includes physical, biogeochemical, and greenhouse gas (GHG) variables measured in surface seawater, such as temperature, salinity, dissolved oxygen, nutrients, chlorophyll-a, pH, total alkalinity, and dissolved inorganic carbon. Concentrations and air–sea fluxes of nitrous oxide (N₂O), methane (CH₄), and carbon dioxide (CO₂) were also quantified. All measurements were conducted following standardized analytical protocols, and certified reference materials and duplicate analyses were used to ensure data accuracy. Consequently, the dataset revealed that elevated nutrient accumulation in port and harbor waters and GHG concentrations tended to be higher at sites with stronger land-based influence. During August 2021, most sites functioned as sources of N₂O, CH₄, and CO₂ to the atmosphere. This integrated dataset offers valuable insights into the influence of anthropogenic and hydrological factors on coastal GHG dynamics and provides a foundation for future studies across diverse semi-enclosed marine systems. Full article

L-thyroxine (T4) is an important hormone for diagnosing and evaluating thyroid function disorders. As outlined in ISO17511, having a certified reference material (CRM) is crucial for ensuring that the results of clinical tests are traceable to the SI-unit. This study employed two principal methods to evaluate the purity of T4, mass balance (MB) and quantitative nuclear magnetic resonance (qNMR), both of which are SI-traceable (International System of Units) approaches. The MB method involved a detailed analysis of impurities, including water, structurally related compounds, and volatile and non-volatile substances. A variety of techniques were employed to characterize T4 and its impurities, including liquid-phase tandem high-resolution mass spectrometry, ultraviolet spectrophotometry, infrared spectroscopy, and both ¹H-NMR and ¹³C-NMR. Additionally, impurities were quantified using Karl Fischer coulometric titration, ion chromatography, gas chromatography–mass spectrometry, and inductively coupled plasma–mass spectrometry. In qNMR, ethylparaben was used as the internal standard for direct value assignment. The results showed T4 purities of 94.92% and 94.88% for the MB and qNMR methods, respectively. The water content was determined to be 3.563% (n = 6), representing the highest impurity content. Ten structurally related organic impurities were successfully separated, and five of them were quantified. Ultimately, a purity of 94.90% was assigned to T4 CRM, with an expanded uncertainty of 0.34% (k = 2). Full article

The carbonate content serves as a fundamental proxy in lacustrine sediments for reconstructing palaeoclimate and environmental changes. Although multiple analytical techniques exist for its quantification, systematic comparisons between different methodologies and the precise identification of carbonate mineralogy are still needed. In this study, a 1020 cm continuous sediment core (YZH-1) from Lake Yangzong in Yunnan Province was employed. Initially, the semi-quantitative calcium (Ca) concentration was obtained via X-ray fluorescence (XRF) core scanning. Subsequently, the total inorganic carbon (TIC) content was determined using both the loss on ignition (LOI) and gasometric (GM) methods to evaluate methodological discrepancies and potential biases. Furthermore, a quantitative regression model was developed to estimate carbonate abundance based on the relationship between XRF-derived Ca data and the analytically determined carbonate content. A comparative analysis revealed a strong positive correlation (r = 0.97) between LOI and GM measurements, though LOI-derived values are systematically elevated by 2.6% on average. This overestimation likely stems from the thermal decomposition of non-carbonate minerals during LOI analysis. Conversely, GM measurements exhibit a ~5% underestimation relative to certified reference materials, attributable to instrumental limitations such as gas leakage. Strong covariation (r = 0.92) between XRF-Ca intensities and the TIC content indicates that carbonate minerals in Lake Yangzong sediments predominantly consist of calcite. A transfer function was established to convert XRF-Ca scanning data into absolute Ca concentrations, leveraging the robust Ca-TIC relationship. The proposed quantification model demonstrates high reliability when applied to standardized XRF-Ca datasets, offering a practical tool for paleolimnological studies in similar geological settings. Full article

Paralytic shellfish poisoning toxins (PSPTs) are a class of neurotoxins most known for causing illness from consuming contaminated shellfish. These toxins are also present in freshwater systems with the concern that they contaminate drinking and recreational waters. This review provides (1) a complete list of the 84+ known PSPTs and important chemical features; (2) a complete list of all environmental freshwater PSPT detections; (3) an outline of the certified PSPT methods and their inherent weaknesses; and (4) a discussion of PSPT toxicology, the weaknesses in existing data, and existing freshwater regulatory limits. We show ample evidence of production of freshwater PSPTs by cyanobacteria worldwide, but data and method uncertainties limit a proper risk assessment. One impediment is the poor understanding of freshwater PSPT profiles and lack of commercially available standards needed to identify and quantify freshwater PSPTs. Further constraints are the limitations of toxicological data derived from human and animal model exposures. Unassessed mouse toxicity data from 1978 allowed us to calculate and propose toxicity equivalency factors (TEF) for 11-hydroxysaxitoxin (11-OH STX; M2) and 11-OH dcSTX (dcM2). TEFs for the 11-OH STX epimers were calculated to be 0.4 and 0.6 for 11α-OH STX (M2α) and 11β-OH STX (M2β), while we estimate that TEFs for 11α-OH dcSTX (dcM2α) and 11β-OH dcSTX (dcM2β) congeners would be 0.16 and 0.23, respectively. Future needs for freshwater PSPTs include increasing the number of reference materials for environmental detection and toxicity evaluation, developing a better understanding of PSPT profiles and important environmental drivers, incorporating safety factors into exposure guidelines, and evaluating the accuracy of the established no-observed-adverse-effect level. Full article

A new type of solid bismuth microelectrode array characterized by eco-friendly properties and the simplicity of its construction is presented for the first time. The proposed array of microelectrodes consists of exactly forty-three single capillaries of an inner diameter of about 10 µm filled with metallic bismuth and packed in one casing. The proposed sensor is reusable thanks to its distinctive design. The microelectrode properties of the proposed working electrodes were confirmed by comparing the analytical signals of cadmium and lead recorded from stirred and unstirred solutions during the deposition step. The practical application of the solid bismuth microelectrode array is presented by detailing the procedure for the simultaneous determination of Pb and Cd by anodic stripping voltammetry. The calibration graphs were linear from 5 × 10⁻⁹ to 2 × 10⁻⁷ mol L⁻¹ and 2 × 10⁻⁹ to 2 × 10⁻⁷ mol L⁻¹ for Cd(II) and Pb(II), respectively (deposition time of 60 s). The detection limits for Cd(II) and Pb(II) were equal to 2.3 × 10⁻⁹ mol L⁻¹ and 8.9 × 10⁻¹⁰ mol L⁻¹, respectively. Potential interferences were investigated. The developed procedure was successfully used for the analysis of certified water reference material and environmental water samples. Full article

Achieving carbon neutrality in the building sector is essential for addressing the global climate crisis. However, the production stage—which contributes to over 29% of a building’s life cycle carbon emissions (CE)—poses significant challenges for consistent carbon performance assessment due to the diversity of building materials and the uniqueness of individual building projects. These factors often lead to inconsistent evaluation results across assessors and the fragmented management of carbon data at the project level. This study proposes the Zero Carbon Building Index (ZCBI), a quantitative assessment method that incorporates embodied carbon from raw material extraction, transportation, and manufacturing. ZCBI enables the evaluation of carbon neutrality performance at the material level and supports the identification of reduction potentials in the production stage. A classification system was developed to evaluate CE during production, creating reference buildings for residential and non-residential purposes. Additionally, a Korean Environmental Product Declaration (EPD) database was established by incorporating CE data from 797 EPD-certified materials. Carbon reduction (CR) and ZCBI values were analyzed by categorizing CE variations across manufacturers into the lowest, average, and highest values. The results showed that CR for apartment complexes ranged from 42.1 to 311 kgCO₂e/m², with ZCBI values between 8.84% and 65.30%, and those for business facilities ranged from 40.9 to 264 kgCO₂e/m², with ZCBI values from 8.59% and 55.43. The proposed ZCBI framework provides a basis for optimizing material selection to reduce emissions and may evolve into a comprehensive carbon neutrality assessment covering the entire construction process. Full article

Matrix certified reference materials (mCRMs) are materials characterized by suitable homogeneity, stability, and traceability, with certified values, including uncertainties, and a specific matrix. mCRMs constitute a reference for instrumental analytical methods and ensure their metrological consistency. Matrix certified reference materials (mCRMs) are essential tools for ensuring the accuracy and traceability of analytical measurements, particularly for samples with complex matrices. These mCRMs are carefully manufactured materials that closely mimic the composition and properties of real samples, allowing laboratories to validate their analytical methods, calibrate analytical instruments, or check the classical methods. This article highlights the challenges associated with the production and characterization of these complex mCRMs, including obtaining homogeneous materials, establishing accurate target values, and ensuring stability for different types of materials, such as gases, liquids, and metal alloys. Additionally, the process of statistical evaluation through the use of advanced statistical methods is discussed, as is the systems approach associated with the implementation of the ISO 17034 standard, which specifies the requirements for manufacturers of reference materials. This paper also includes a summary of the current status in trends of normalization as well as mCRM production. Full article

Honey is increasingly recognized not only as a functional food but also as a potential bioindicator of environmental pollution. This study assessed the concentrations of four potentially toxic elements (PTEs)—lead (Pb), cadmium (Cd), copper (Cu), and zinc (Zn)—in 48 multifloral honey samples collected in 2023 from seven locations across a historically polluted agro-industrial region in Romania. Samples were analyzed using Flame Atomic Absorption Spectrometry (FAAS) and Graphite Furnace AAS (GFAAS), with quality control ensured through certified reference materials. Results revealed that Pb (0.72–1.69 mg/kg) and Cd (0.02–0.37 mg/kg) levels consistently exceeded international safety thresholds, while Cu (0.62–2.22 mg/kg) and Zn (0.91–1.93 mg/kg), although essential nutrients, were found in elevated concentrations. Spatial analysis indicated a general trend of higher contamination in sites located closer to former industrial facilities, influenced by factors such as altitude and atmospheric transport. These findings confirm the persistent environmental burden in post-industrial landscapes and support the use of honey as a cost-effective tool for pollution monitoring. The study underscores the need for targeted environmental policies, sustainable apicultural practices, and continued surveillance to protect ecosystem health and food safety. Full article

This study focused on the measurement of anthropogenic radionuclides such as americium (Am) and plutonium (Pu) in environmental samples. Plutonium isotopes, particularly ${}^{239}\mathrm{Pu}$, ${}^{240}\mathrm{Pu}$, and ${}^{241}\mathrm{Pu}$, originated from nuclear weapons testing, nuclear power plants, and accidents like Chernobyl and Fukushima Daiichi. Accurate measurement of these isotopes, considering their half-lives and trace concentrations, provides critical information about their persistence and environmental transport. Using the 1 MV Tandetron accelerator, we expanded the measurement capabilities to include ${}^{241}\mathrm{Pu}$, ${}^{241}\mathrm{Am}$. Chemical separation of these isotopes was achieved through ion chromatography, employing reference isotopes ${}^{242}\mathrm{Pu}$ and ${}^{243}\mathrm{Am}$ for method validation. Certified reference materials, including IAEA-410 (Bikini Atoll sediment) and Sample 05, were analyzed to ensure accuracy. We validated the ${}^{241}\mathrm{Am}$/${}^{243}\mathrm{Am}$ ratio in an Am standard (IFIN-STD-Am, our laboratory produced standard for Am), achieving a measured value of 0.158 at·at⁻¹ (3%), in good agreement with the nominal value of 0.154 at·at⁻¹. Additionally, we determined the ${(}^{241}\mathrm{Pu}$ + ${}^{241}\mathrm{Am}){/}^{242}\mathrm{Pu}$ ratio in the ColPuS standard to be equal to 0.029 at ·at⁻¹ (7%). These results demonstrate the potential of AMS for improved detection of actinides at low concentrations and contribute to understanding the behavior of Pu and Am isotopes. Full article

A certified reference material (CRM) for aflatoxins (AFTB1, AFTB2, AFTG1, AFTG2) and zearalenone (ZEN) in corn/peanut blended vegetable oil (GBW(E)100863) was developed to address the critical need for matrix-specific reference materials in mycotoxin analysis. The CRM was prepared by blending naturally contaminated corn and peanut oils, followed by homogenization, sterilization, and sub-packing. Homogeneity and stability studies were conducted using high-performance liquid chromatography isotope-dilution tandem mass spectrometry with a dilute-and-shoot pretreatment process. The CRM demonstrated excellent homogeneity and stability, with no significant degradation observed under either short-term (65 °C for 14 days) or long-term (25 °C for 12 months) storage conditions. An inter-laboratory comparison involving six authoritative laboratories confirmed the CRM’s accuracy and reliability, with recovery rates ranging from 90.3% to 97.3% and low relative standard deviations (RSDs) of 3.79% to 7.99%. The CRM provided a robust metrological tool for mycotoxin analysis in complex oil matrices. This study not only enriches the national reference materials library but also supports food safety initiatives by facilitating accurate and reliable mycotoxin detection in vegetable oils, thereby enhancing regulatory compliance and public health protection. Full article

Calibration is crucial in quantitative analysis, ensuring the traceability of standards for an accurate comparison of results. In mercury determinations, a gas calibrator unit containing liquid mercury is used for calibration by injecting headspace volumes via syringe. The Dumarey equation has been used for over 35 years to calculate mercury headspace concentration, aligning closely with saturated vapor pressure equations. However, the 2006 Huber equation yields different values, creating discrepancies. This paper compares calibrations using the Dumarey equations against NIST 3133 certified reference material, with detection by a cold vapor atomic fluorescence spectrophotometer (CV-AFS). The gas standard was injected directly, while Hg^II in NIST 3133 was reduced to Hg⁰ and captured on gold traps. Across 10–24 °C, the Hg⁰ concentration was determined, with uncertainties ranging from 2.9% to 8.4% for a coverage factor of two. No significant differences were found between calibrations using NIST 3133 and the Dumarey equation. These findings provide crucial insights into the traceability and accuracy of mercury calibration methods, ensuring the reliability of measurements used for environmental monitoring and regulatory compliance. Full article

Carotenoids are essential bioactive compounds in plant-based foods, valued for their antioxidant properties and role in human health. Accurate quantification of these pigments is critical for food science, nutrition, and health research, yet their analysis remains challenging due to structural complexity, susceptibility to degradation, and matrix interferences. This review comprehensively evaluates analytical techniques for carotenoid assessment, focusing on chromatographic advancements, emerging detection strategies, and sustainability considerations. High-performance liquid chromatography remains the gold standard due to its precision, while novel approaches such as supercritical fluid chromatography and core–shell particle technology enhance efficiency and environmental sustainability. Machine learning and lab-on-a-chip technologies are also emerging as promising tools for rapid, cost-effective, and miniaturized analysis. Challenges in standardization, regulatory gaps, and the limited availability of certified reference materials persist, emphasizing the need for fully validated analytical methodologies. Future research should prioritize green analytical techniques and interdisciplinary strategies to improve sensitivity, reproducibility, and environmental impact. This review provides a critical resource for researchers and industry professionals willing to refine carotenoid analysis for food science, nutrition, and biotechnology applications. Full article

Spray-on fireproofing materials (SFRMs) and intumescent paints are commonly used to enhance the fire resistance of steel structures. Despite extensive studies on the performance of SFRMs and intumescent paints, there remains a significant lack of research on the material properties of certified products used in real-world applications, especially according to exposed temperatures. In this study, heating experiments were conducted to investigate the material properties of two widely used certified materials in Korea, focusing on their application thickness and exposure temperature. The experiments set target temperatures ranging from room temperature to 900 °C in increments of 100 °C. Additionally, various material properties, such as changes in shape and the insulation performance of the SFRM and intumescent paint, were observed at each temperature. Notably, the moisture content and discoloration depth of the SFRM displayed a consistent trend under different exposure temperatures, a material property that has not been previously reported. Furthermore, the insulation performance of the two materials differed by approximately 17% to 25% compared to an uncoated specimen exposed to the same temperature. The findings on the properties of SFRMs and intumescent paint relative to the exposure temperature presented in this study can serve as valuable data for selecting materials to improve fire resistance performance across various construction sites in the future. Additionally, they can act as key reference data in the diagnostic evaluation process for assessing the impact of fire on steel structures. Full article

This paper shows the fabrication of a new environmentally friendly sensor, an activated glassy carbon electrode with an in situ deposited bismuth film (aGCE/BiF), to determine Cd(II) and Pb(II) at the nanotrace level. The electrochemical activation of the GCE surface was achieved in a solution of 0.1 M phosphate-buffered saline (PBS) of pH = 7 by performing five cyclic voltammetric scans in the range of −1.5–2.5 V at ν of 100 mV/s. The newly developed electrode provides several advantages, such as an increased electron active surface (compared to the glassy carbon electrode) and improved electron transfer kinetics. As a result, the new voltammetric procedure (square-wave anodic stripping voltammetry, SWASV) was established and optimized. With the SWASV method, the following calibration curves and low detection limits (LODs) were obtained for Cd(II) and Pb(II), respectively: 5–100 nM, 0.62 nM, 2–200 nM, and 0.18 nM. The newly prepared method was used to determine the amounts of Pb(II) and Cd(II) in the certified reference material, and the results agreed with the certified values. Moreover, the procedure was successfully applied to determine the Cd(II) and Pb(II) in river samples. The official and standard addition methods validated the measurement results. Full article